Molecular sieve manufacturer talks about the application of molecular sieve in PVC and CPVC heat stabilizers
Natural molecular sieves are mined from volcanic tuff deposits. Because when this mineral powder is heated, crystal moisture will escape from the interior, resulting in a phenomenon similar to bubble boiling, hence the name - molecular sieve. In industry, natural molecular sieves have been used as ion exchangers, adsorbents and catalysts, as well as paper and plastic fillers, animal feed additives, soil improvement absorbents, especially in environmental protection (such as water treatment) Broad application prospects. However, only a few of the more than 60 kinds of natural molecular sieves (such as oblique molecular sieves, mercerized molecular sieves, wool molecular sieves, diamond molecular sieves, sheet molecular sieves, calcium cross molecular sieves, etc.) have been found.
Since the quality of natural molecular sieves cannot meet the increasing demand for quality in industry, synthetic molecular sieves have replaced natural molecular sieves in many applications. The main elements of synthetic molecular sieves are silicon, aluminum and sodium, and hydrogen and oxygen exist in the form of crystal water. According to different needs, metal ions such as zinc, magnesium, calcium, strontium and nickel can be introduced (in place of sodium), and anions such as perchlorate, phosphite and other organic acids can also be introduced to improve the desired performance. The most basic structural unit of the molecular sieve framework is the TO4 tetrahedron, and the central atom T of the tetrahedron is most commonly Si and Al, and can also be Ga, B, Ti, Fe and other elements.
Because elements such as sodium, aluminum, and silicon can be combined in any proportion, theoretically, there can be infinite varieties of molecular sieves. At present, there are hundreds of molecular sieve varieties synthesized in the world (many varieties are often called molecular sieves). Molecular sieves are also divided into many types. As auxiliary stabilizers for PVC resins, there are mainly A type, X type and Y type. Because of their strong Lewis basicity on the particle surface, strong gravitational force of cage structure, and ion exchange ability. Molecular sieve with these properties is an excellent auxiliary heat stabilizer for PVC. The current synthesis technology and specific preparation methods can effectively improve these properties, and can meet the processing requirements of PVC and CPVC resins to a great extent.
At present, the output of PVC resin in the market is very large, and the products of CPVC resin are also increasing rapidly. However, they are easy to decompose during processing, especially CPVC, and the release of sodium chloride will accelerate the decomposition of the resin, so CPVC has higher requirements for stabilizers. Therefore, many people are engaged in the research of heat stabilizer recently. Since the new century, many high-efficiency stabilizers have appeared in China, which can better meet the processing needs of soft and hard PVC resins. At present, PVC and CPVC heat stabilizers mainly rely on organotin and lead salts, but both tin and lead are toxic heavy metals, and the price of organotin is relatively high. Therefore, replacing tin and lead or reducing the proportion of tin and lead in the stabilizer will be the development direction of the stabilizer in the future. Under the current technology and market conditions, inorganic stabilizers such as hydrotalcite and hydrocalumite will be a good choice, but the price of these raw materials is too high, so molecular sieve will be the best choice, both with excellent thermal properties Stable and inexpensive.
In recent years, people's research on molecular sieves has been in-depth, especially in molecular sieves and catalysts, there have been many research results. Hunan Providence New Materials Co., Ltd is a professional molecular sieve manufacturer
which can provide USY zeolite, NaY zeolite, REY zeolite, ZSM-5 zeolite, welcome to consult.